Not something I am too worried about since it easy to write around it, but would it be possible to impliment this dicussion:
Hopefully this will be in the next releasem and will operate when the filename given is "-" ie
rndr - < myRib.rib
will do what you want - though it will not be possible to combine this with network renders which need to ship the rib to other server instances.
I made a small addition to George's solution. Pixie can now read the input from stdin without the "-" argument.
So rndr < myRib.rib should work now.